SOURCE: ZIMBIO                                                                                                                                                             (Getty)

Even before she checked herself into a rehabilitation center for "physical and emotional issues" last November, Demi Lovato was open about the pain she'd faced at the hands of tormentors during her childhood.

Lovato, 18, says she was bullied constantly by classmates until she left school to finish her studies at home. In an interview with ABC's Robin Roberts (via Us Magazine), Lovato said, "I literally didn't know why they were being so mean to me. And when I would ask them why, they would just say, 'Well, you're fat.' I was bullied because I was fat. And then a few months later I developed an eating disorder, and that's kind of what I've been dealing with ever since."

Lovato has had issues with food for a decade, starting with compulsive overeating at the age of 8. In other interviews, she has acknowledged that her eating disorder is something she'll have to confront for the rest of her life.